Determinative Tables
(a) Transmitted Light
| Mineral | Color | Relief | Birefringence | Other |
|---|---|---|---|---|
Plagioclase |
colorless |
low |
1st order gray |
polysynthetic twinning |
Olivine |
colorless |
high |
2nd order yellow |
melt inclusions |
Clinopyroxene |
tan to red-brown |
high |
1st order red to 2nd order blue |
optically zoned, commonly fractured |
Orthopyroxene |
colorless |
high |
1st order yellow |
parallel cracks, difficult to distinguish from olivine |
Pyroxferroite |
yellow |
high |
1st order yellow |
rare, spongy texture ,found adjacent to glass or silica in mesostasis |
Silica |
colorless |
very low |
gray |
cracked |
Glass |
variable |
- - - |
isotropic |
many colors including colorless |
Pleonaste |
red |
very high |
isotropic |
zoned, high reflectivity |
Zircon |
colorless |
very high |
gray |
unzoned, high reflectivity |
Phosphate |
colorless |
low |
gray |
needles and spongy masses in mesostasis |
(b) Reflected light
| Mineral | Color | Reflectivity | Anisotropy | Other |
|---|---|---|---|---|
Ilmenite |
gray |
high |
strong |
most abundant opaque in lunar samples, thin laths are slightly transparent, red-brown |
Chromite |
brownish-gray |
high |
isotropic |
hexagonal outlines, often overgrown by ulvöspinel |
Ulvöspinel |
brown |
high |
isotropic |
hexagonal outlines, frequently exsolved |
Rutile |
light gray |
high |
high little |
exsolution lamellae in ilmenite |
Armalcolite |
gray |
high |
moderate |
hexagonal barrel-shaped habit |
Tranquillityite |
gray |
high |
isotropic |
tiny laths in glassy, mesostasis, slightly transparent red |
Fe-Ni metal |
bright white |
very high |
isotropic |
frequent blebs in troilite |
Troilite |
yellow |
very high |
strong |
soft, scratches |